Fluid meter



M? 22 1945 J. c. STEVENS 2,376,459

FLUID METER Filed Aug. 18, 1942 4 Sheets-Sheet 1 2 5 0 2 0 3 j l CROSSv REFERENCE EXAWMNER May 22, 1945. J. c. STEVENS 2,376,459'

' FLUID METER Filed Aug. 1a, 1942 4 sheets-sheet 2 1g l 21T La m 'z2 Il 1 n u I0/i12 Illa/ens 2 5 o 2 o 3 @m85 REFERENC UAM'NER May 22, 1945- J. c. sTEvENs 2,376,459

FLUID METER Filed Aug. 1e. 1942 4 sheets-sheet s im l/lla Illa/ems' Z 5 U f 2 O 3 CRGSS REFERENCE A EXAMINER May 22 1945- J. c.`-sTEvEN$ 2,376,459

FLUID METER y l Filed Aug. 18, 1942 4 Sheets-Sheet 4 ,I/211 Y lleven:

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Patented May zz. 194s FLUID METER 1 John C. Stevens, Portland, Oreg., assigner to Leupoid Stevens Instruments, Portland, Oreg.,

p consisting of had Leupold, Mar- Robert J. Stevens, and John C.

Appleman mi 1s, mz, sum No. 45am c cum. (ci. rs-zos) forth. One of the most widely used instruments l in this connection is the manometer which serves directly to measure pressure and may, when used with venturis or restricted orifices. serve also to indicate a function of velocity. The manometer,

despite its wide spread use, is subject to several l important' limitations. In the tlrst place, the pressure differentials indicated by the manometer 'are'transitory in nature and require the attend- .ance of an observer at all times if any record is to be maintained of fluctuations in either pressure or velocity covering any substantial period of time. Furthermore, the shanks of a manometer ,tube indicate a' pressure or a pressure difierentia., as such, and additional calculations are station remote from the column oi liquid to be measured.

It is a further object of this invention to provide apparatus for the measurement and registration oi' the level of columnsof liquid irrespective of the association of the column with a measuring instrument of the manometer type.

Other objects and advantages of this invention will be apparent upon a consideration oi' the foilowing detailed description of various embodiments thereof in conjunction with the annexed drawings wherein:

Figure 1 is a view in front elevation of registering apparatus constructed according to this invention showing the same in association with a column ot liquid'in a transparent tube, the front cover of the housing surrounding a portion of the apparatus being removed for convenience of illustration;

Fig. 2 is a top plan view of the apparatus shown in Figure i, the top cover of the housing being removed for convenience of illustration;

Figure 3 is a view similar to Figure 2, but including diagrammatically the circuits controlling necessary if these indications are to be read in 35 the opera-1011 0f the leistefi terrnsof velocity. Despite these limitations, the mano ,ieter, because oi' its simplicity and reliability, persists as the most popular instrument of its kind.

However, because of the above limitations of l the manometer, a wide variety o! indicating, registering and recording apparatus has been developed for the purpose of recording pressure or velocity data covering long periods of time as Figure 4 illustrates schematically an adaptation of this invention to the registration of liquidl levels in a reservoir:

Figure 5 illustrates schematically an adaptation of' this invention to the measurement of ilowv or velocity ina pipe line;

Figure 6 illustrates schematically a modied form of the invention including means for protecting a manometer liquid from contamination well as to render available direct indications of when measuring now velity;

velocity. Such apparatus, in use, has met with indifferent success, usually due to the complexity of the structures and the incident tendencies toward failure and maladjustment.

It is therefore an object of this invention to overcome the difllculties heretofore encountered in the registering and recording of data correlated with liquid levels and to provide an instrument in which the advantages of the manometer are retained while its limitations are overcome.

According to this invention, it is contemplated that pressure diflerentials indicated by a manometer may be registered or recorded in terms of functions of pressure as weil as pressure itself,

and that such registrations may be recorded over long periods of time without the attendance of an operator.

It is further contemplated that the registrations and/or recordations may be made at a 6I Figure '7 illustrates schematically a modification oi' the invention for recording and totalizing the flow of water through a Venturi tube by registering the actual differential head of water; and

Figure 8 is a detail view of a portion of the apparatus shown in Figure 7.

Referring in greater detail to the construction of Figures 1 to 3, inclusive, the numeral 9 designates a transparent pipe or tube containing an opaque liggjd Il, the surface level of which is to measured. The tube may one eg a n :uuu l'" I may be Otherwise connected to a liquid system so that the height o! the liquid II in the tube l will give an indication of pressure or some functionv of an unknown.

Surrounding tube t is a rectangular housing generally` indicated at il. ed to move vertically along the axis oi tube l and to this end it is provided with bars il andl l) attached respectively to its top and bottom Housing Il is daptattheirendsasmaybeseeninl'igure2forthe purpose of receiving guide 'rails l2 which may be.bolted or otherwise suitably fastened to a support lla.

Interiorly, housing l l is subdivided by a horizontal partition l1 into upper and lower compartments I2 and i2, respectively. Upper compartment i2 in turn is divided into three smaller compartments 22, 2| and 22 by vertical partitions 22, 22 and 2l. Partitions 22, 22 and 22 extend inwardly from the vertical side walls of housing to a centrally located opaque tubular member 22 which surrounds tube 2 and acts as a further guide for housing il which is axially movable along said tube. Tubular member 22 extends vertically from slightly above top cover |2 of housing to a point slightly below partition I1.ascanbeseeninlllgure 1. Itshould be noted, however, that tubulanmember 22 does not fully enclose the portion oi tube 2 which passes through compartment |2 for one side oi tubular member 22 is provided with a. round aperture at 21 located approximately in align lment with partition 22, while on the opposite side of tubular member 22, two sight windows 22 and 22 are provided. Sight windows 22 and 22 in tubular member 22 are both in registry with round aperture 21 which is of suiiicient Idiameter to encompass them. Sight windows 22 and 22 are horizontally spaced and somewhat verticallyoifsetascanbeseeninFlgure 1.

It is contemplated that housing Il and all of the partitions therein be of opaque material, particularly partitions 22, 22 and 22, cover plate |2 and shelf I1 which denne compartments 22, 2| and 22. '.libular member 22 is likewise of opaque material so that light can be transmitted from compartment 22 to compartment 2| only through apertures 21 and 22, while transmission from compartment 22 to compartment 22 is similarly possible only through apertures 21 and 22. Partition 22 abuts tubular member 22 between sight windows 22 and 22 so that there is no light connection between compartments 2| and 22.

In compartment 22, a light source such as an ordinary incandescent bulb 22 is located. This light source is arranged to direct light rays through aperture 21, transparent tube 2 and sight openings 22 and 22 into compartments 2| and 22, respectively. In compartments 2| and 22- photo-electric cells 2| and 22 are positioned adjacent sight windows 22 and 22, respectively. Thus it is that in the absence of opaque liquid |2 in transparent tube 2, cells 2| and 22 may be simultaneously energized by light issuing from the source at 22.

Housing is suspended by a chain 22 which passes upwardly over a sprocket 22 keyed to a shaft 22 which carries additionally gears 22 and 21. Shaft 22 is shown more or less schematically ,polecausestherotortoturninons S REFERENCE andshortingthecorrcspondingcoilcnthsothe pole causes it to turn in the opposite direction. It is contemplated that the direction oi rotation and the initiation ot rotation of motor 22 balcontrolled by photo-electric cells 2| and 22 in a' manner to be hereinafter more fully set forth.

Gear 22 which is mounted on shaft 22 meshes with a gear 2| which drives, through a flexible cable 22, a registering or recording instrument 22 of a type such as shown in any one ci' the iollowing patents: J. C. Stevens, 1,356,322; J. C. Stevens, 1,303,120; J. C. Stevens, 2,099,180; J. C. Stevens, 2,000,048: and J. C. Stevens, 1,494,034. It will be unerstood, of course, that the construction of the register or recorder at 22 forms no part of the present invention.

It has been stated that light impingement on photo-electric cells 2| and 22 can control the operation oi motor 22 and that the operation of this motor will bring about movement of housing and. a recordation through apparatus 22. In this connection, it has also been previously stated that liquid I2, a column of which is confined in tube 2, is opaque. Thus, if the level of liquid I2 is above the top of sight opening 22, no light will reach either of cells 2| and 22. On the other hand, if the liquid level is below the bottom edge of sight opening 22, light will impinge simultaneously on both of the cells. It is for this reason that sight openings 22 and 22 are vertically offset so that the liquid may assume a position such as that shown at b-b in Figure l. wherein sight opening 22 is substantially closed to light while sight opening 22 is open. Thus photo-electric cell 2| may be energized while photo-electric cell 22 is not. The condition illustrated in Figure 1 is the condition of equilibrium in which the rotor of motor 22 is immobilized.

'I'he manner of operation of motor 22 from photoelectric cells 2| and 22 will be apparent upon reference to the circuit diagrams in Figure in Figure l, but it is, of course, contemplated that nected through a gear 22`with gear 21. Motor 22 may be one of any number of commercial types but is preferably of the split phase type, the field of which is continuously energized. In this 3. Radio tubes 22 and 22 are operatively connected to the sensitized plateof photoeelectric cell 2| so as to amplify the current generated by light falling on the sensitized plate of said cell. Radio tubes 22 and 21 perform a similar function with respect to photo-electric cell 22. 'I'he circuits leading from radio tubes 22 and 22 are..l

connected to a relay 22 having a switch element 22 normally biased to closed position by a spring 22. Switch element 22 of relay 22 controls the circuit to shading coil BI in the field of motor 22. Shading coil 22 of motor 22 is similarly controlled by a switch element of a relay 22 which element, however,is normally biased to open position by a spring 22, the thrustof which may be overcome by the electromagnet operatively connected to radio tubes 22'and 21 which in turn amplify the generations of photo-electric cell 22. Motor 22 is, as illustrated, of the split phase type having a continuously energized neld 22a serving to energize by induction whichever of the shading coils 2| or 22 is in a closed circuit. If relay 22 is deenergized and the switch is closed at 22 shading coil 2| will be in a closed circuit and capable of energization in the same manner as the secondary of a transformer. 'Ihis will impart to the squirrel cage armature 2lb a bias in one direction. If, on the other hand, switch 22 is closed the same situation will obtain with respect to shading coil 22 causing the armature to be biased in the other direction. When the circuits to EXAMINER aavaasa 3 both shading coils Il and l! are open no rotation It can be seen that when the opaque liquid il in tube l is at the level b-b shown in Figure 1,.

light is substantially shut of! from photo-electric cell I2, while light may reach photo-electric cell 3l. The electric current emanating from photoelectric cell ll, ampliiled through radio tubes u and I5, serves to energize relay 4l and thereby open switch element 49 against the normal bias of spring l0. In this condition, the circuit of shading coil 5I is open. At the same time, photo-electric cell 32 is not energized so that spring 55 maintains switch element 5I in open position and thereby maintains open the circuit of shading coil 52. Since both shading coils in the field ci motor 39 are open, the rotor thereof remains stationary so that shaft l! is not driven and no recording or movement of housing Il occurs.

If, at this time, opaque .liquid il rises in the tube 8, it will shut oi the light through sight window 28 to photo-electric cell 3l. 'I'his releases the amature of relay 4l thereby causing switch element I9 to close the circuit to shading coil Il under the urging of spring Il. Thus, a rise in the liquid level in tube l will cause the rotor of motor 38 to turn in a direction to raise housing il and the entire assembly mounted therein until the relative positions of the photo-electric cells and the liquid level reach the equilibrium point as illustrated in Figure 1.

If, on the other hand, the opaque liquid in tube i falls with respect to housing Il and the photoelectric cells mounted therein, sight opening 2l is eilective so that light passes from source ll to photo-electric cell 32. Under these circumstances. relay 54 closes the c ircuit to shading coil l! causing the rotor of motor I9 to turn in a direction to bring about the loweringof housing il to the equilibrium position. In both cases. rotation of shaft l5 makes a registration or recording automatically and in the absence of an operator.

' The width A and relative positions of sight openings 2l and 29 determine the sensitiveness "of the apparatus. Thus. fluctuations of, for example, .0l of a foot or less or of .05 of a foot or more of the surface of liquid lli in tube 0 may be permitted without disturbing the balance and causing the motor to be operated to thereby operate the register or recorder.

The combination of photo-electric cells and a reversing motor can be adapted to recording and/or indicating not only liquid levels, but the rategfdggwand the total volumi;n of flow wherever the liquid levels o'tl'idinil'erence of two levels are an index; ofsuch flow. A i'ew auch adaptations are illustrated in Figures 4 to 8, inclusive. hereinafter described.

In Figure 4 there is shown an adaptation of the present invention to the registration of levels in a reservoir generally indicated by reference character Il. From a point beneath the level oi' the liquid in the reservoir, a tube il leads to a leg 58 of a manometer II, the other leg Il of which is provided with an assembly such as that described in Figures 1 to 3. inclusive. The head in the reservoir is balanced 'by mercury in the lmanometer II.. The photo-electric cell assembly follows the surface of the mercury inleg IU and'its rise h above the balance position of the mercury a-a is proportional to the total head h. The gear that drives the sprocket wheel also turns a spur gear which drives an indicator or recorder of any suitable type. The indicator may be cali-` of i'low of water in a pipe through a restricted oriilce. In this instance, a U-manometer Il is partially lled 'with mercury or some other immiscible liquid heavier than water and rendered opaque in any suitable manner. The legs of manometer Il are connected to a pipe I2 on opposite sides of a plate I3 defining an orifice within the pipe of lesser diameter than the diameter oi' the pipe. An assembly such as that shown in Figure 1 is operatively connectedon the low pressure leg of manometer li which, of course, must be transparent. The photo-electric cell assembly follows the surface of the liquid in this leg of the manometer registering the distance h above balance line a.-a which is proportional to the total differential head of water on the orifice which in turn is a function of the rate of flow of the water through the orifice. Motor I9, which moves the photo-electric cell assembly, also actuates an indicator or recorder of any suitable type.. not shown, which may register and totalise flow. While the construction of Figure 5 has been described in conjunction with the iiow of a liquid through pipe line i2, it is apparent that a similar assembly can be used to measure the flow of gas through a restricted orifice in a pipe line.

In Figure 6, there is shown an adaptation of the present invention to the measurement oi' the flow of a liquid, such as sewage, containing contaminants which would foul the manometer if the liquid were allowed to come in contact with the column of measuring liquid. A sewage pipe line Il is provided with a. venturi' at A manometer has one leg thereof connected by pipe Il to the low pressure zone or throat of the venturi IU while the other leg is connected by a similar pipe il to the high pressure or upstream side of the venturi.- A gas tank 89 is provided and this tank is connected by pipes 10 and 1I to pipes l1 and Il, respectively. Pipes 10 and 1i are provided with needle valves12 and 13 adjacent the points of connection to pipes Il and Il. It is con l, templated that tank 89 be illled with a colorless iiuid under high pressure, for example. liquidi) carbon dioxide, compressed airnitrogen, and forth. Needle valves 12 and 'Il are then ve slightly opened to allow a gas leakage into the 4leads I1 and Il to the venturi 65, as indicated by the gas bubbles in Figure 6. Manometer Bt may be filled to the balance line a--a with any opaque liquid suchas water and the like containing a suitable dye. Clearly, when gas bubbles into the upstream end' of the venturi l5, the pressure in the leg of the manometer connected thereto is equal to that at its point of connection to the venturi. Similarly, the pressure inthe manometer leg connected to the throat of the Venturi tube is equal to the throat pressure thereof. An assembly such as that described in Figure 1 .is mounted on the low pressure leg of manometer Il. The position of the assembly above the balance line o-a measures the head h which is proportional to the differential head on the Venturi tube and is also a function of the flow of sewage through it. Since the gas pressure equals the Pressure of sewage, a gas seal is interposed beinvention to recording and totalizing the ,einem el. me

flowoftheiiquidthroughaventuritubebyregisiering the actual diiferential head of liquid in it. regardless of the pressure inthepipe. A'Venturitube'llisprovidedinapipeline'ilcarrying afiowofliquid. Aconduit 1l leadsfromtheupand l'l are provided with shut-oil valves 1I and 1l. respectively. Manometers Il and Il serve respectivelythehighandlowpressuresonesofthc venturi.

V Interpoaed between conduit 'It and manometer Il, there is a frusta-conical tank l2 supported on a beam Il which may be placed at dierent heights by bolting to vertical bars Il and Il which are provided with a plurality of vertically spaced apertures for this purpose. The height of the liquidinthetankdependsupontbepressureinpipe line 1I. The top of tank l! is connected by pipe 'llwiththetopsofthemanometertubeslland Il. A valve Il is for the purpose of letting air into tank Il. When valve l1 is closed, the tube Il is. of course, air-tight when tank l2 is empty of liquid and full of air, and valve 'Il is open, waterwilliiowfromthe highpressuresideof venturi'liandcompressairintheupverportion of tank l2 and in pipe line Il. This prevents the liquid in manometer Il which is connected by a pipe line Il to the bottom of tank I2 from rising above the liquid level in that tank. vOf course, the airpreureonthe topofmanometerll isthe sameasthatontopofmanometerllbutsince thethroatpressureinventurillatthepointof connectionofpipe'll ialessthanthatatthepoint of connection of pipe 10, the liquid level in nmnometer Il will be lower than in :nanometer Il byadistancehwhichiscommonlycalledthe' Venturi head. Itwillbeunderstood that head -acamwithintherecorderhousingcausthepen tomoveproportionaltotherateofilowwhich is asingie valued function ofthe head h. Within `the'recorder is a totalising mechanism which is operated by the combined action of a time vclock and the photo-electric cell assembly such that the total volume ofilow is rea'istered'by the re- I eerder. In this way. the recorder is caused to ristenthermnow andthe total volume of reference u mun v, it wm be noted that conduit Il is not connected directly to manometer ll,`nor is conduit 'Il directly connectedtomanomeierlL Onthe contrary. housingsliandffareinterposedthedetails ofwhich maybeviewedinl'igurel. Housings Iiandn being identical. the description will be-conilned llleadsintosealed housing fl. Withinthehousingisaiiexblebsglhthe interior'of which is connected to the tube of :nanometer Il by a short connection I4. Except i theapparstusisnrstputlntouse.

of bynuts It. Aplug llaervesasanairventwhen thatilexibiebag I8 constitutes ameansofse'sregating the liquid in manometer Il from the liquid in tank I2. Thus, liquid entering housing UI under'pressure will compress flexible bag n causl ing the latter to elect the dyed nanometer liquid thepressureinhousingil drops. resilientbagll expands drawing manometer liquid into itself and lowering the height of the column in ma- 15 nometer Il.

Theadvantageinusingtheconstnictionof Figure 8 instead of an alternative pian involving opaque goats on the liquid surface of the ma'- nometers is that the photo-electric cell assembly mucho met meu u the come: position after a power interruption during which the liquid levels might have undergone material change rn order to prevent euiauon of un liquid surface in themanometenaportionofthetube -on the discharge side of the housing is coiled and of small diameter. Of course. by this arrangementanydegreeofdampingispoasible.

The advantages or interposing tank pressure aoliinthelinetotheupstreamtapoftheventuri istolengthenthetimeoipperationwithoutresetting the photocell housings. Under pressure airisdissolvedbythewaterandcarriedouta'sthe water levels nuctuate. The liquid levelsin both :nanometers will therefore continue to rise althoughthediiierenceintheirlevelsalwavsshows thecorrectheadontheventuritubeororifice. Whenthelevelslnthehighpressuremanometer risessohighthatthephoto-electriccellassem 4o bly can no longer follow it, valves in the lines tothemanometertubesareclosedandthepressuretankisemptiedofwaterthroughablowoif valve 4III and filled lwith air through valve Il. When water is again'allowed to now into the 'pressuretanhtherelativelevelsinthemanometers areloweredtotheiroriginalposition.

There is some advantage in using a conical pressuretankbecausethepipelinepressuremsy thenvarywidely withoniymoderate ductuations 5 in the liquid in the high procure :nanometerwhosesmfacelsaiwaysatthesamelsvelasthat inthepreluretank. l

Althoughinthespecincationandtheaccompanyingdrawingsthereisshownanddescribed apreferredembodimentoftbisinventionand various modifications thereof, and although various alternatives are suggested,4v these are not in- Vtendedtobeexhamtiveiioi'limiting oftheinvention, but, on the contrary. are given for the purposeofillustratingitandinstructingothers-in A theprinciplesthereofaswellasthebestpractical Y manner of utilising the invention in order that othersmaybeenabledtomodifyitandlwlit innumerousformseachasmaybebestsuited astoconditionsandreqmrementsinanypar- Whatisclaiinedis: 1 .Inafiowregisteringdeviceinciudinga measuring means wherein the drop inprenure is 7 an index of the rate of flow. a pair of stationary -manometers with transparent walls connected re' spectively to the highv and low pressure sides of l the measuring device. a housing surrounding each manometer ,and siidable therealong. alight source and a pair of photo-electric cells disposed eter, a column of liquid in each manometer the level of which determines the amount of light reaching each oi' the pairs oi cells from their source and a pair of photo-electric cells disposed in each housing on opposite sides of each manometer, the level of the opaque liquid in each manometerdetermining the amount of llight respective light source. allait 'of reversible 'nio'tor's,l` I f 'reaching each 'oi' the pairs of cells from their rediilerential gearing connecting the rotors of the spectiyelight source, a pair of reversible'mo'tors, two motors. cell controlled means resporlsive'to i:iiigerentialgearing connecting fthe rotors oi the one relative position ofnthe1-zcellsiinaone'hoi`sfing motors; fceil controlled-means responsive to and the column of liquidginth'e respectivefmnom'- one relativejposition 0i ille cells in one Ihousing eter for immobilizing one' Uf. sid'rmotorsw's'aid nl u means causing actuation orz-.said:motoi= movement of said cellseanci,coluinnawyeifnilx'r-i` said one relative positiomithe A.'iirection' oT-le'lafL sind the'cplumn of liquid inthe respective' mah npnieter`i'ofimmobilizing one4 of said motors, said means ,causing actuation of said motor upon fovement of said cells and column away from tive movement controlllngzthezeitectiledriving fffsaid one 'relative position, the direction of reladirection oi' said motor, corresponding meanfsn'- fijlve; movement controlling the effective driving trollingrthe other motor irom Lthe'lllquid level in' fdiljegtiongoi said motor, corresponding means conthe other manometer,r meanslire'sponsivt fthe' i lljginsitiielother .motor` from `the liquid level in actuation of each motorior. restoring thefrepecj; fiiejeiher nanometer. means l resDOnSiVe t0 the tive housing and the cellsethereinolthatreltive j eetuelflen. QfeeehmOtOrfOrrestoring the resDeeposition with respect to theliduidnthemnm-f '29 tij/ lt ilouelnnd the cells therein to that relative eter which it surrounds inwhich the the' motor is i 'gdelliioniwith' respect to the liquid in the menemimmobilized, and means 'driven by sa'iddireneiiel' which ritsurrouncls in Wllehl the motor is tial gearing for registering theadiilere irl-'levelslv .'jllnmdblllzed, und means driven by Seid difierenc 1;.: -v .gal gearing for registering the difference in levels -of the liquids in the two manometeisff-T-"e- 2. In a ow registering: devicefincluding've 2o 0f the liquids in the two manometers. measuring means whereindzhe dr'op in pressue's 1i, in ja 'liquid level registering device including an index of the rate of illrw, aadir-Jol stationary Olumn o!! Opaque liquid in a translucent vertimanometers with transparentA w'a'lls corlcte` i H cal tuba@ B support mountedfor movement respectively to the high anddow re's'sr Tsi-des uffi-he lube. e light source carried by of the measuring device,'afhousin'g'surrounding 3 ll ee ldjj8upp9.l'll on one side of said-tube, e' Pair of each manometer and slidable'thereaiong-alightf;piiotoelectric 1cells attached to said support at source and a pair of photo-electricV cells `dissed j-flgeeedwpoints thereon at approximately the Seme in each housing on opposite sides'o'f'eacli niinprrr-` jjjjleYel ee lille light Beuree 8nd 0n the ODPOSite side eter, a column of liquid nly 'each manometer the ""Uf the tube i'l'm Seid light SOuICei' receive light level cf which determlnes'tllelanlcnr ffllght ee directly iremthe lisht source through the tube, reaching each of the pairs icellsf-romt'ieil'reboth'eljlseld eellS beins in elitnment 'with said speotive light source, a pair-o'f'r'ersible'motors fughe eeln'ee through Seid lube e Vertical Derdifferentiallgearing ccnnecting-th'e-rotrs ofthe ,jl'llloe belleenihe. Jelle` end extending adjacent two motors, cell controlled means''sponsive to' tlieiffuleeo Separate the cells, amask joining one relative position oi' ther'cells iT-nehousing j 'eem Perline end extending laterally fl'Om the and the column of liquidintherespective ma? jj Pelftlllen t0. ne between the-light Source und One nometer for; immobilizing one of'sidmto`s saidj Pf'sekleeus and enel'hel' mask e150 lolnlng Seid means causing actuation-inf Zsaid`='x'x1 `:t`or `uponiv Partition end. ellfendlng leeelelly' from the Dertimovement of said cells andcolumnav'vlrv om on n? e mecum substantially OPPOSlle from llle I *W "w-flret meek to lie between the light source and the said one relative positionfthe direction oi rela-V th .n .am i t tive movement controllintheeiective'drivingfj er 's masks and'partition hereby P` direction of said motor, corresponding meansgcon-, 'lle'mgdtouforg "parate compfathment fg flach trolling the other motor from--th'e'liQuClJleVeU-n VVVling an'opelings tllrhoulafl: onea lreigesl andaln the other mammelle!" mem`mpns1vej9 the .50 the line oi' thev lissage of light from the light f actuation ofeaeh meter felifeellel'lngllle'eslee iV-isour'ce to the coresponding cell and the otherf tive housinggand the cells tlierein totl 1a;11e1atiye, ,Il mask having an opening therethmugh at a du- Peslllen with, respecta thexlluldln. tllenienel' ferent 'level and in lthe line o! the passage of eter Whlehleeunwnde mwmel'lllelnelenl-Slm Y light from the iight source vto the other cell, a meblllzed means driven byeifdiqefenlil gear' eymotor.' `cell controlled means responsive to one me fer registering the .offline relative position ofsaid cells and said column for Mulde in the two manemetes'eld ineens f9.1 Aimmobilizing said motor, said means causing acconvertins the dlileienee Of-ievele'lnte ef `lsuation orsaidvmotor upon relative movement of "etes of now and totalizedqm'f .J-rnc 1- said cells and column away from said one rela- 3. In e liquid level registering devlee lnelillmg lilly tive meigiQmlhe direction of relative movement a ilow measuring device lnewhlellflle mer-@Ee controlling the egfective driving direction of the .of two pressures is an illldcilrfui-A flowfe Pell 0f "l motor, means establishing a driving connection transparent walled manometersfonerconneeled, l, T between said motorand'said Support so that the t0 the hlh Pressure Side endl'flle'flhet? L `support is moved by the motor to restore the cells low pressure side oi the flow mowing 'del/leef; 'eejtothe one relative position in whlclithe motor 1s an opaque liquid in each manoniciieiA theevelefij Liminobillediand "means responsive to actuation which is controlled by the pressure in the meas-j -l je: j the motor 'forl registering, .indicia correlated urins dee at the point otatttgchget binne-g twith thelevel ofthe column.: A 1 manome a pressure tanklin'- e "g firessure if ggglnja" liquid level'registerin'gdevice includline, an 'air-tight. connection between tha-tank 79' ingpafcolumnotlopaque liquid' in a translucent a and the tolle of the two manometeralthe @lineej tube, agligll'tlsource on onel side, 'of said tube,v a tumori mounted; for J movement lengthwise c: the tulpe,` a'pair ofphotoelectric .cells attached to said support et. spaced Points, thereon. l both of allant-Jl saidcells being in alisnmentwith .said light each :nanometer and slidablatherealonu c l H f ze source through seid tube, s motoncell controlled mesnsresponsivetoonerelstivepositionofssid cells snd said column i'or immobilizing said motor, seid means causing sctustion of seid motor upon relstive movement ot seid cells snd column sway from seid one relstive position. the direction of relstive movement contxolling the eilective driving direction o! the motor, means estsb lishing s driving connection between said motor snd ssld support s0 that the support is moved by the motor to restore the cells to the one relative positioninwhichthemotorisimmobilized,snd means responsive to actuation of the motor for resislering indlcis correlated with the level ot the column, the improvement which comprises, s sleeve surrounding ssid tube und attached to said support, lsid sleeve hsving s psir of vertically offset horizontally spaced light openings on one side thereof und s single light opening on the other side thereof in resistry with said pair, and s plurslity ci lisht mssks extending radially from ssid sleeve Ind isolating said cells from each' other und each cell from the light source except through seid tube, sold light' source being mounton seid support sdiscent the single opening. 8. In e registering device wherein pressure dii'- -terentislissnindexofthediitstoberegistereclI s pair of ststionsry :nanometers with trsnsperent wells connected respectively to the high und lqvpressm'esbetvssnwhichthediirerentisiis tobemessured.shousingsurro\mdingeschme nometer end slidsble thereslons. lisht emitting meenssndspsirotphotoelectric' cells disposed in each housingon opposite sides o! escb msthe level of which determinesthe amount of lisht rescbingeschotthepsirsotcellstmmtheir inssndthecolumnolliouidintherespective msnometer for immobilising one o! seid motors,

seid mesns causing sctuetion of said motor upon movement of seid cells und ssid column swsy from seid one xelstive position. the direction o! relstive movement controlling the eilective drivs column of liquid in esch msnometer. 

